Safety latch



Sept 21 1965 w. E. BARTLETT 3,207,541

SAFETY LATCH Filed July 15, 1963 INVENTOR. WILLIAM E. BARTLETT ,MMO R NEYS United States Patent O 3,207,541 SAFETY LATCH William E. Bartlett,8547 Meyers, Detroit, Mich. Filed `uly 15, 1963, Ser. No. 294,898 16Claims. (Cl. 292-220) This invention relates to a latch and moreparticularly to a safety latch which is adapted for use with medicinecabinets or the like to effectively prevent children of relativelytender age from opening the cabinets. Heretofore no latch has beenavailable which was complicated for children to operate but simpleenough for persons attaining the age of reason to operate if they knewthe sequence required for opening the latch. While combination locks andkey operated locks and latches are available none of them are completelysuccessful due to the fact that the combination of the lock may beeasily lost as is also the case with the key of a key operated lock. Inaddition the key or combination may not be readily available when it isrequired to obtain certain of the contents from the cabinets.

With the present invention, unauthorized manipulation of the latch isrendered diicult, if not impossible, by children under six years of agethereby providing a safe and effective means for protecting the childrenfrom the medicine, poison or the like stored in the cabinet.

It is an object `of the present invention to provide an improved latchwhich possesses the characteristic of safety to a marked degree andwhich is practically impossible to operate by a child of tender age.

Another object of the present invention is to provide a safety latchhaving a latching element engageable with the jamb of a door frame orthe like and a shaft which loosely carries the latching element wherebythe shaft is turned in one direction while an axial force is appliedthereto and then in the opposite direction while an axial force isapplied thereto before the latching element is released.

Still another object of the present invention is to provide a safetylatch having latch and unlatch positions comprising a housing, anelongated shaft mounted in the housing for rotational movement and foraxial movement, said housing including a pair of oppositely facingabutments which are spaced from the shaft, alignment means carried bythe shaft, a pair of elements in the housing loosely mounted on theshaft including a latching element and an operating element, each of theelements having an opening therein adapted to receive the alignmentmeans, resilient means operatively connected to the elements for urgingthe operating element against one of the abutments and the latchingelement against the other of the abutments which corresponds to thelatch position, said shaft being rotatable in one direction towards saidone abutment while an axial force is applied thereto until the alignmentmeans on the shaft is received in the opening in the operating elementand thereafter rotatable in the opposite direction towards the otherabutment along with the operating element while an axial force isapplied thereto as before until the alignment means carried by the shaftis also received in the opening in the latching element, said shaftthereafter being rotatable in said one direction along with both of theelements to a position limited by the engagement of the elements withsaid one abutment which corresponds to the unlatch position.

A further object of the present invention is to provide a safety latchof the aforementioned type wherein additional resilient means is locatedbetween the housing and the shaft for biasing the shaft to a positioncorresponding to the latch position where the alignment means is spacedaxially from the elements.

Another object of the present invention is to provide a safety latch ofthe aforementioned type wherein a revil) 3,2%?,541 Patented Sept. 2l,1965 leasable lock is carried by the housing engageable with the shaftto limit or prevent complete axial movement thereof when the latch is inthe latch position.

Still another object of the present invention is to provide a safetylatch of the aforementioned type wherein a stop abutment is carried bythe operating element closely adjacent the opening therein, said stopabutment being engageable with the alignment means or key on the shaftfor preventing rotation of the shaft in said one direction once thealignment means or key thereon has been moved axially towards theoperating element and rotated past the opening or key-way therein.

A further object of the present invention is to provide a safety latchof the aforementioned type wherein each of the resilient means is in theform of a spring.

It is thus another object of this invention to provide a simplified lowcost structure of the aforementioned type having certain advantagescontributing to efficiency, safety, reliability and long life as well asease of maintenance.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawing, illustrating a preferred embodiment of theinvention, wherein:

FIGURE 1 is a vertical sectional view of the safety latch.

FIGURE 2 is an end elevation of the safety latch with the cover plateremoved and looking in the direction of arrows 2-2 of FIGURE l.

FGURE 3 is a sectional view taken substantially on the line 3 3 ofFIGURE l.

FIGURE 4 is a pictorial view of the safety latch, illustrating themanner in which the component parts are assembled and certain structuralfeatures of the invention.

Referring now to the drawing, the latch is designated by the numeral 10and is illustrated as being mounted on a door 12 of a medicine cabinetor the like. The latch 1t) is provided with a mounting flange 14 whichis adapted to engage the inside surface of the d-oor 12 as bestillustrated in FIGURE l. A plurality of screws or bolts 16 threadedlyconnect the latch 10 to the door 12.

The door 12 is provided with a circular opening Ztl which receives theboss 22 which extends outwardly from one side of the mounting plate orflange 14. The boss 22 is of circular cross section and is substantiallyhollow. An interior transverse wall 26 is provided in the boss 22 and isprovided with a centrally located circular opening 28. Extendinginwardly from the other side of the mounting plate or ilange 14 is anouter cylindrical cover or part 30 which forms part of the latchhousing. A cover plate 32 provided with a centrally located circularopening 34 is attached to the outer end of the cylinder part 3i) bymeans of a plurality of circumferentially spaced screws or bolts 36. Theflange 1li, boss 22, cylinder part 30 and cover plate 32 form the latchhousing.

An elongated shaft 4@ extends centrally through the housing includingthe boss 22, and openings 28 and 34. The wall 26 is provided with arecess 42 of substantially rectangular cross section. The shaft 40 isprovided with alignment means in the form of a key 44 of rectangularcross section which is adapted to be received in the recess 42, as bestillustrated in FlGURE l, for limiting the outward movement of the shaft40. This position results when the latch 10 is in the latch position.The outer end of the shaft i0 is provided with a handle or knob 42 whichis connected to the shaft 40 by a pin or set screw 43. Part of the knob42 includes a knurled flange 48 for rotating and `axially moving theshaft 40 as will subsequently appear. The cylindrical part Si) of theknob 42 is tubular and includes an inner Wall 51 which is spaced fromthe shaft 40 to dene a spring cavity 52. A biasing spring 54 isinterposed around the shaft 40 between the surface 56 of the partitionor wall 26 and the wall 58 of the knob 42 for biasing the shaft 40 in anoutward direction to the limiting position which is determined by theengagement of the key 44 with the end wall of the slot 42 as bestillustrated in FIGURE 1.

' Mounted within the interior of the housing formed by the outercylinder part 30 and cover plate 32 is an inner cylinder part 60 whichis concentric with the outer cylinder part 30. The inner cylinder part60 extends throughout more than 180 as best illustrated in FIGURE 3 andhas its center on the elongated axis of shaft 40. The opposite ends ofthe inner cylinder part 60 form a pair of oppositely facing abutments 62and 64. The cylinder part 30 is provided with a notch or groove 66having end walls 68 and 70.

Located within the housing are a pair of elements or washers includingan operating element 74 and a latching element 76 `which are looselycarried by the shaft 40. The operating element 74 has a centrallylocated opening 7S for receiving the shaft 40. A key-way 79 is providedinthe operating element 74 in communication with the opening 78. Theoperating element 74 includes an outwardly extending lug 80 which isprovided with an integral spring tab S2. The latching element 76includes a centrally located circular opening 86 having in communicationtherewith a key-way 88. In addition, the latching element 76 includes aradially extending elongated prong or tang 90 which extends through theslot 66, as best illustrated in" FIGURE 2 when the latching element ismounted on the shaft 40. The latching element 76 also includes anintegral spring tab 92. The prong 90 effects the latching action betweenthe door 12 and the door frame as is conventional in the art.

The operating element 74 is located immediately adjacent the mountingflange 14 while the latching element 76 is located adjacent the coverplate 32 as best illustrated in FIGURE 1. Resilient means such as thespring 94 is provided for biasing the latching element 76 to a latchposition. The spring 94 has one end connected to the spring tab 82 andthe other end connected to the spring tab 92, with the .spring 94extending around the outer periphery of the inner cylinder part 60. Thelatch is illustrated in a latch position in FIGURE 2, with the lug 80having a side 96 biased against the abutment 64 Aprovided on the innercylinder part 60 and the latching element 76 having a side 98 biasedagainst the other abutment 62 provided on the inner cylinder part 60.When the latch 10 is in the latch position, the key 44 is spaced axiallyfrom the operating and latching elements.

The operating element 74 is provided with a stop pin or abutment 100 onthe side thereof facing the wall 26. The stop abutment 100 is locatedclosely adjacent one edge of the key-way 79 for the specific purpose ofengaging and camming the key 44 into the key-way 79 as will subsequentlyappear.

The latch housing carries as an extra safety precaution a shiftablelocking device 102 which includes a pivoted stop element 104 and ahandle 106 which are operatively connected by a pin 103. Rotation of thehandle 102is effective to shift the stop element 104 towards and awayfrom the shaft 40 into and out of the path of movement of the knob 42.The locking device 102 may be placed at any convenient location to workin conjunction with the shaft 40 and knob 42 so that the locking device102 must be released, as an example, before the last inward movement ofthe shaft 40 engages the latching element 76 in the process of openingthe latch 10. The particular design of the locking device 102 may varydepending on the location thereof.

When it is required to operate the latch 10, it is necessary to bringthe key or the alignment means 44 into contact with the key-way providedin both of the elements 76 and 74. Since the key-ways 79 and 88 providedin the operating and latching elements are not in alignment with the key44, it is necessary to not only move the shaft 40 axially, toward theleft as viewed in FIGURE 1, but

4 also to rotate the shaft 40 in one direction so as to bring the key 44first into alignment with the key-way 79 provided in the operatingelement 74 and thereafter rotate the shaft 40 in the opposite directionwhile continuing to apply an axial force so as to bring the key 44 intoalignment with the key-way 88 provided in the latching element 76. Thissequence of operations is accomplished only after releasing the lockingdevice 102. Thereafter, the shaft 40 and the operating element 74 andlatching element 76 which are now coupled to the shaft are rotated inthe opposite direction to effect the release of the latching element 76.

Assume that thelatch 10 is in a latch position with the door 12 closedas illustrated in FIGURES 1-3 and it is required 'to open the door 12.As mentioned previously when the latch is in the latch position theoperating element 74 has a side 96 abutting the stop abutment 64 and thelatching element 76 has a side 98 abutting the stop abutment 62 due tothe provision of the spring 94.

The following description of the operation of the latch applies whenlooking in the direction of" arrow A in FIGURE' 1. Initially, thelocking device 102 is released so as to move the element 104 out of thepath of movement of the knob 42. An axial inward force is applied to theshaft 40 thereby moving the key 44 out of the slot 42 :and thereafterrotating the` shaft 40 in a clockwise direction while continuing toapply the axially inwardly directed force to the shaft 40. As a resultthereof the key 44 engages the stop pin or abutment 100 which indicatesto the person operating the latch that the key is in close proximity tothe key-Way 79 as provided in the operating element 74. Due to thelocation of the stop pin 100 it is effective to cam the key 44 into thekey-way 79 as long as the axial force is continued. Upon engagement ofthe key 44 with the key-way 79 provided in the operating element 74 theshaft 40 is rotated in -a counterclockwise direction thereby moving theoperating element 74 in the same direction away from the stop abutment64. The shaft 40 is rotated in the counterclockwise direction While 4anaxial inwardly directed force is applied thereto so as to bring thealignment means or key 44 to a position opposite the key-Way 88 providedin the operating element 76 and nally into engagement with the keyway88. At this time the shaft 40 has been moved to its inwardly limitingposition. Thereafter, the shaft 40 and the coupled elements 74 and 76`are rotated in the clockwise direction so as to move the latch element76 away from the stop abutment 62,to effect the release of the latch.The amount of movement is determined by the engagement of the prong 90on the latching element with the Wall 70 of the slot 66 provided in theouter cylinder part 30 or preferably by engagement of the lug with thestop abutment 64, depending on the clearances and tolerances involved inthe construction of the latch.

It will, of course, be appreciated that when the axial force is appliedto the shaft 40 that the spring 54 is compressed. are rotated the effectof the spring 94 is overcome.

Once the force has been removed from the shaft 40 the spring 54 iseffective to return the latch to the piston illustrated in FIGURE 1. Inother words, the spring 54 urges the key 44 out of the key-ways 79 and88. 'Ihereafter, the spring 94 returns the operating element 74 andlatching element 76 to the position illustrated in FIGURE 2. Later onthe locking device 102 is moved to the position illustrated in FIGURE 1such that if a person would again apply `an .axial force to the shaft 40the stop element 104 would engage the left-hand end of the knob 42thereby preventing further inward movement of the shaft 40.

In the sequence of opening thelatch, if the shaft 40 is rst movedaxially against the operating element 74 and then turned in acounter-clockwise direction, the key 44 will be moved against theabutment 100. If the counterclockwise motion is continued, the element74 can 'be In addition, when the elements 74 and 76.

moved over to the stop abutment 62., and will come to rest against it.The key 44, cannot engage the key-way 79 when the shaft 4@ is moved in acounter-clockwise direction. The key 44 will only engage the keyway 79when the shaft 40 is turning in a clockwise direction, when looking atthe latch in the direction of the arrow A in FIG. 1.

It will be appreciated that at any time during the `operating sequenceof opening the latch, if the axial force is removed, the latchingelements will return to the latched position and the sequence of openingthe latch will have to be started over again.

Referring once again to the operation of the latch it should be notedthat if the person fails to `apply an axial force to the shaft 44) whilerotating same in a counterclockwise direction after engaging theoperating element 74, that the key 44 fails to mesh with the key-way 88in the latching element 76 and as a result thereof the shaft 40 isrotated past the key-way S8 to a position determined by the engagementof the surface 110 provided on lug 80 with the lstop abutment 62. This,of course, will depend on the relative angular distance between thekeyways 88 and 79 when in a position corresponding to the latchposition. This is an additional and optional safety feature for thelatch lil.

It should be appreciated that the latch is fairly easy to operate if -aperson knows the sequence of operation. A person who has attained theage of reasoning could still operate the latch with a little imaginationand perseverance. However, it should be appreciated that a child ofrelatively tender age would find it extremely diicult if not impossibleto actuate the latch 10.

The drawing and the foregoing specication constitute `a description ofthe improved safety latch in such full, clear, concise and exact termsas to enable any person skilled in the art to practice the invention,the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. A safety latch having latch and unlatch positions comprising ahousing, an elongated shaft mounted in said housing for rotationalmovement and for axial movement, said housing including a pair ofoppositely facing abutments which are radially spaced from said shaft,alignment means carried by said shaft, a pair of elements in saidhousing provided with holes through which said shaft extends, saidelements being loosely mounted on said shaft to permit axial movement ofsaid shaft with respect to said elements and including a latchingelement and an operating element, each of said elements having anopening therein adapted to receive said alignment means, resilient meansoperatively connected to said elements for urging said operating elementagainst one of said abutments and said latching element against theother of said abutments which corresponds to the latch position, saidshaft being rotatable in one direction towards said one abutment whilean axial force is applied thereto to move said shaft axially withrespect to said elements until the alignment means on said shaft isreceived in the opening in said operating element and thereafterrotatable in the opposite direction towards said other abutment alongwith said operating element while an axial force is applied thereto asbefore until the alignment means carried by said shaft is also receivedin the opening in said latching element, said shaft thereafter beingrotatable in said one direction along with both of said elements to aposition limited by the engagement of said elements with said oneabutment which corresponds to the unlatch position.

2. The safety latch defined in claim l wherein resilient means isprovided between said housing and said shaft for biasing said shaft to aposition corresponding to the latch position where said alignment meansis spaced axially from said elements.

3. The safety latch defined in claim 2 wherein said last-mentionedresilient means is in the form of a spring.

4. The safety latch defined in claim 1 wherein a releasable lock iscarried by said housing engageable with said shaft to prevent axialmovement thereof when the latch is in the latch position.

5. The safety latch dened in claim 1 wherein a stop abutment is carriedby said operating element closely adjacent the opening therein, saidstop abutment being engageable with the alignment means on said shaftfor preventing rotation of said shaft in said one direction once thealignment means thereon has been moved axially towards said operatingelement and rotated past the opening therein.

6. The safety latch defined in claim 1 wherein said resilient means isin the form of a spring.

7. A safety latch having latch and unlatch positions comprising ahousing, an elongated shaft mounted in said housing for rotationalmovement and for axial movement, said housing including a pair ofoppositely facing abutments which are radially spaced from said shaft onone side of the axis thereof, a key on said shaft, a pair of elements insaid housing provided with holes through which said shaft extends, saidelements being loosely mounted on said shaft to permit axial movement ofsaid shaft with respect to said elements and including a latchingelement .and an operating element, each of said elements having akey-way therein, resilient means operatively connected to said elementsfor urging said operating element against one of said abutments and saidlatching element against the other of said abutments which correspondsto the latch position, said shaft being rotatable in one directiontowards said one abutment while an axial force is applied thereto tomove said shaft axially with respect to said elements until the key onsaid shaft is received in the key-way in said operating element andthereafter rotatable in the opposite direction towards said' otherabutment along with said operating element while an axial force isapplied thereto as before until the key on said shaft is also receivedin the key-way in said latching element, said shaft thereafter beingrotatable in said one direction along with both of said elements to aposition limited by the engagement of said elements with said oneabutment which corresponds to the unlatch position.

S. The safety latch defined in claim 7 wherein resilient means isprovided between said housing and said shaft for biasing said shaft to aposition corresponding to the latch position where said key is spacedaxially from said elements.

9. The safety latch defined in claim 8 wherein said last mentionedresilient means is in the form of a spring.

lil. The safety latch dened in claim 7 wherein a releasable lock iscarried by said housing engageable with said shaft to prevent axialmovement thereof when the latch is in the latch position.

11. The safety latch delined in claim 7 wherein a stop abutment iscarried by said operating element closely adjacent the opening therein,said stop abutment being engageable with said key for preventingrotation of said shaft in said one direction once the key has been movedaxially towards said operating element and rotated past the key-wayprovided therein.

12. The safety latch dened in claim 7 wherein said resilient means is inthe form of a spring.

13. A safety latch having latch and unlatch positions comprising ahousing, an elongated shaft mounted in said housing for rotationalmovement and for axial movement, said housing including a pair ofoppositely facing abutments which are radially spaced from said shaft onone side of the axis thereof, a key on said shaft, a pair of elements insaid housing provided with holes through which said shaft extends, saidelements being loosely mounted on said shaft to permit axial movement ofsaid shaft with respect to said elements and including a latchingelement and an operating element, each of said elements having a key-waytherein, resilient means operatively connected to said elements forurging said operating element against one of said abutments and saidlatching element against the other of` said abutments which correspondsto the latch position, said shaft being rotatable in one directiontowards said one abutment while an axial force is applied thereto tomove said shaft axially with respect to said elements until the key onsaid shaft is received in the key-way in said operating element andthereafter rotatable in the opposite direction towards said otherabutment along with said operating element while an axial force isapplied thereto as before until the key on said shaft is also receivedin the key-way in said latching element, said shaft thereafter beingrotatable in said one direction along with both of said elements to aposition limited by the engagement of said elements with said oneabutment which corresponds to the unlatch position, resilient meansbetween said housing and said shaft for biasing said shaft to a positioncorresponding to the latch position where said key is spaced axiallyfrom said elements, a releasable lock carried by said housing engageablewith said shaft to prevent axial movement thereof when the latch is inthe latch position, and a stop abutment carried by said operatingelement closely adjacent the opening therein, said stop abutment beingengageable with said key for preventing rotation of said shaft in saidone direc- Vtion once the key thereon has been moved axially towardssaid operating ,element and rotated past the key-way therein.

14. A safety latch having latch and unlatch positions comprising: ahousing having a mounting plate, a pair of "concentrically arrangedcylinder parts extending in one direction from one side of said plateand arranged substantially perpendicular thereto, a hollow bossextending in the opposite direction from the other side of said mountingplate, an interior transverse wall in said boss having an openingtherein, and a cover plate attached to the outer cylinder part andhaving an opening therein aligned with the opening in said wall; anelongated shaft mounted in said housing for rotational movement and foraxial movement, said shaftextending through the openings in said walland said cover plate; the inner cylinder part having an angular extentgreater than 180, with the ends thereof forming a pair of oppositelyfacing circumferentially spaced abutments; a notch in the outer edge ofthe outer cylinder part; a key on said shaft; a pair of elements in saidhousing provided with holes through which said shaft extends, saidelements being loosely mounted on said shaft to permit axial movement ofsaid shaft with respect to said elements and including a latchingelement and an operating element; each of said elements having a key-waytherein; said operating element being carried by said shaft within thespace defined by said cylinder parts and including a lug having sidesengageable with the abutments on said inner cylinder part; said latchingelement being carried by said shaft within the space defined by saidcylinder parts and including a tang which extends outwardly through saidnotch (and having sides engageable with the sidesof said notch; a springsurrounding the outer periphery of said inner cylinder part and havingone end thereof connected to the lug of said operating element and theother end connected to said latching element for urging said operatingelement against one of Vsaid abutments and said latching element againstthe other of said abutments which corresponds to the latch position;said shaft being rotatable in one direction towards said one abutmentwhile an axial force is applied thereto until the key on said shaft isreceived in the key-way in said operating element and thereafterrotatable in the opposite direction towards said other abutment alongwith said operating element while an axial force is applied thereto asbefore until the key on said shaft is also received in the key-way insaid latching element, said Shaft thereafter being rotatable in said onedirection along with both of said elements to a position limited by theengagement of said elements with said one abutment which corresponds tothe unlatch position.

15. A safety latch having latch and unlatch positions comprising: ahousing having a mounting plate, a pair of concentrically arrangedcylinder parts extending in one direction from one side of said plateand arranged substantially perpendicular thereto, a hollow bossextending in the opposite direction from the other-side of said mountingplate, an interior transverse Wall in said boss having an openingtherein, and a cover plate attached to the outer cylinder part andhaving an opening therein aligned with the opening in said wall; anelongated shaft mounted in saidphousing for rotational movement and foraxial movement, said shaft extending through the openings in said walland said cover plate; the inner cylinder part having an angular extentgreater than with the ends thereof forming a pair of oppositely facingcircumferentially spaced abutments; a notch in the outer edge of theouter cylinder part; a key on said shaft; a pair of elements in saidhousing provided with holes through which said shaft extends, saidelements being loosely mounted on said shaft to permit axial movement ofsaid shaft with respect to said elements and including a latchingelement and an operating element; each of said elements having a key-Waytherein; said operating element being carried by said shaft within thespace defined by said cylinder parts and including a lug having sidesengageable with the abutments on said inner cyl- Vinder part; saidlatching element being carried by said shaft within the space defined bysaid cylinder parts and including a tang which extends outwardly throughsaid notch and having sides engageable with the sides of said notch; aspring surrounding the outer periphery of said inner cylinder part andhaving one end thereof connected to the lug of saidoperating element andthe other end connected to said latching element for urging saidoperating element against one of said abutments and said latchingelement against the other of said abutments which corresponds to thelatch position; said shaft being rotatable in one direction towards saidone abutment while an axial force is applied thereto to move said shaftaxially with respect to said elements until the key on said shaft isreceived in the key-way in said operating element and thereafterrotatable in the opposite direction towards said other abutment alongwith said operating element while an axial force is applied thereto asbefore until the key on said shaft is also received in the key-way insaid latching element, said shaft thereafter being rotatable in said onedirection along with both of said elements to a position limited by theengagement of said elements with said one abutment which corresponds tothe unlatch position; a knob carried by said shaft; a spring surrounding'said shaft engageable with said transverse wall and said knob forbiasing said shaft to a position corresponding to the latch positionwhere said key is spaced axially from said elements; and a releasablelock carried by said housing engageable with said knob to prevent axialmovement of said shaft when the latch is in the latch position.

16. The safety latch defined in claim 15 wherein a stop abutment iscarried by said operating element closely 4adjacent the key-way therein,said stop abutment being engageable with the key on said shaft forpreventing rotation of said shaft in said one direction once the key hasbeen moved axially towards said operating element and rotated past thekey-way therein.

References Cited by the Examiner UNITED STATES PATENTS 1,843,013 1/32Buettner 70--219 M. HENSON WOOD, JR., Primary Examiner,

1. A SAFETY LATCH HAVING LATCH AND UNLATCH POSITIONS COMPRISING AHOUSING, AN ELONGATED SHAFT MOUNTED IN SAID HOUSING FOR ROTATIONALMOVEMENT AND FOR AXIAL MOVEMENT, SAID HOUSING INCLUDING A PAIR OFOPPOSITELY FACING ABUTMENTS WHICH ARE RADIALLY SPACED FROM SAID SHAFT,ALIGNMENT MEANS CARRIED BY SAID SHAFT, A PAIR OF ELEMENTS IN SAIDHOUSING PROVIDED WITH HOLES THROUGH WHICH SAID SHAFT EXTENDS, SAIDELEMENTS BEING LOOSELY MOUNTED ON SAID SHAFT TO PERMIT AXIAL MOVEMENT OFSAID SHAFT WITH RESPECT TO SAID ELEMENTS AND INCLUDING A LATCHINGELEMENT AND AN OPERATING ELEMENT, EACH OF SAID ELEMENTS HAVING ANOPENING THEREIN ADAPTED TO RECEIVE SAID ALIGNMENT MEANS, RESILIENT MEANSOPERATIVELY CONNECTED TO SID ELEMENTS FOR URGING SAID OPERATING ELEMENTAGAINST ONE OF SAID ABUTMENTS SAID LATCHING ELEMENT AGAINST THE OTHER OFSAID ABUTMENTS WHICH CORRESPONDS TO THE LATCH POSITION, SAID SHAFT BEINGROTATABLE IN ONE CDIRECTION TOWARDS SAID